Stemming in rock blasting refers to filling the space above the explosive charge in a drill hole with an inert material, such as crushed rock, sand, or clay, to seal the hole. This practice serves to contain the explosive energy, directing it towards the rock mass and reducing the likelihood of premature venting of blast gases.
Stemming provides the confinement of explosive energy for a longer duration than in a blast hole without it. The most important function of stemming is to maintain the explosive energy within a blast hole and reduce the energy loss from the borehole (Baluch et al., 2024). A good stemming minimizes vibration and noise by reducing the amount of explosives used (Baluch et al., 2024).
Without stemming, up to 50% of the explosive energy can escape through the borehole (Brinkmann, 1990). Missing or improper stemming, which leads to detonation gas escaping from blast holes in advance, results not only in the wastage of explosive energy and poor fragmentation but also in environmental problems such as ground vibration, noise, flying rocks, back breaks, and air blasts (Floyd, 1999).
According to (Baluch et al., 2024), stemming, which maintains gas pressure over time, is used to enhance a blast’s performance. Additionally, excellent stemming can effectively extend the action period and the range of the detonation gas in the borehole by preventing premature overflow of the borehole with the detonation gas.
Reference
Baluch, K., Park, H.-J., Kim, J.-G., Ko, Y.-H., & Kim, G. (2024). Enhancing Rock Blasting Efficiency in Mining and Tunneling: A Comparative Study of Shear-Thickening Fluid Stemming and Plug Device Performance. Applied Sciences, 14(13), Article 13. https://doi.org/10.3390/app14135395
Brinkmann, J. R. (1990). An experimental study of the effects of shock and gas penetration in blasting. Proceedings of the 3rd International Symposium on Rock Fragmentation by Blasting, 55–66.
Floyd, J. L. (1999). Explosive energy relief–the key to controlling overbreak. Procs. Int. Conf. Explo, 99, 147–153.
